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Why is Message Queuing failing after the December 2025 Windows update?
System administrators managing Windows Server environments may have recently observed critical failures within the Message Queuing Service (MSMQ). These disruptions, characterized by misleading storage errors and service inactivity, stem directly from the security updates released on December 9, 2025. Microsoft has acknowledged this regression and released emergency out-of-band (OOB) updates to restore functionality.
Technical Analysis: The Root Cause
The core issue originates from alterations Microsoft implemented regarding the MSMQ security model and NTFS permissions. Specifically, the December update modified access controls for the directory C:\Windows\System32\MSMQ\storage.
These permission changes inadvertently block the system’s ability to write necessary data, particularly in clustered environments operating under high load. Consequently, the system generates false-positive error logs indicating “insufficient storage or memory,” even when hardware resources remain abundant.
Identified Symptoms:
- Queue Inactivity: MSMQ queues cease processing unexpectedly.
- IIS Failures: Internet Information Services sites crash with “Not enough resources” errors.
- Write Failures: Applications fail to write data to queues.
- Creation Errors: The system cannot generate message files, specifically citing the path C:\Windows\System32\msmq\storage*.mq.
Remediation Strategy: Out-of-Band Update Deployment
To resolve these MSMQ failures, administrators must apply the specific out-of-band update corresponding to their operating system version. These patches are not distributed via standard automatic updates and must be manually retrieved from the Microsoft Update Catalog.
Action Plan:
- Identify your specific Windows Server or Windows 10 version.
- Locate the corresponding Knowledge Base (KB) number in the table below.
- Download and install the update to revert the permission conflict.
| Operating System Version | Required Update (KB) |
|---|---|
| Windows 10 22H2 ESU / Enterprise LTSC 2021 | KB5074976 |
| Windows Server 2019 / Enterprise LTSC 2019 | KB5074975 |
| Windows Server 2016 / Windows 10 LTSB 2016 | KB5074974 |
| Windows Server 2012 R2 | KB5074978 |
| Windows Server 2012 | KB5074980 |
| Windows Server 2008 R2 | KB5074977 |
| Windows Server 2008 | KB5074979 |
Installing these patches immediately corrects the security model misalignment, allowing the Message Queuing service to resume normal operations without manual permission overrides.